1. Field of the Invention
This invention relates to an improvement of an automatic perimeter for measuring the visual field by exhibiting a target mark on an inner surface of a dome which constitutes a part of a target mark exhibiting device.
2. Description of the Prior Art
Heretofore, there is known an automatic perimeter for measuring the visual field by exhibiting a target mark on an inner surface of a dome which constitutes a part of target mark exhibiting means. FIG. 11 shows one example of such conventional automatic perimeter. In FIG. 11, the numeral 1 denotes a visual field measuring apparatus body, 2 a housing and 3 a hemispherical dome. A target mark projecting mechanism (not shown) is disposed within the dome 3. A target mark spot light emitting means 4 is disposed on a rear surface side of the dome 3 within the housing 2. The target mark spot light emitting means 4 has a spot light projecting light source. The dome 3 is provided at a front portion thereof with a panel 5. A face portion receiving hole 6 adapted to receive a face portion of a subject is formed in the panel 5. The face portion receiving hole 6 is provided with a face receiving member 7 adapted to fix a face portion. The face receiving member 7 has a forehead contacting portion 8 and a chin receiving portion 9. When testing, the subject places his forehead and chin on the forehead contacting portion 8 and on the chin receiving portion 9, and then inserts his face portion into the face portion receiving hole 6. The subject receives a test by visually confirming an exhibited target mark while fixedly gazing at a fixation mark which is projected on an inner surface 10 of the dome 3. An inspector designates a projecting position, brightness, etc. of a target mark spot projected on the inner surface 10 of the dome 3 by operating various kinds of control switches mounted on instruction means 11 and a light-pen 12.
In an automatic perimeter, when a static visual field measurement is performed, a target mark is usually exhibited on the inner surface 10 of the dome 3 in accordance with a standard inspection pattern (for example, quick screening pattern). However, depending on the results of inspection based on the standard inspection pattern, there are sometimes cases in which a particular area needs to be designated for further detailed inspection. In such a case, a target mark to be exhibited is added or changed. Heretofore, as shown in FIG. 12, a rectangular area 15 is selected as an adding or deleting area of an inspecting point by designating two points on a diagonal line as shown by "X" marks on a display screen 13 of a display device of the instructing means 11. The lattice points 14 within the rectangular area 15 are regarded as inspecting points to be added or deleted, and one or more target mark positions to be exhibited on a target mark exhibiting means by determining the inspecting points. Target marks corresponding, one by one, to the inspecting points are exhibited on the target mark exhibiting means for inspection.
However, in the conventional automatic perimeter, the inspecting points to be added or deleted are limited to those located within the rectangular area 15. Further, a complicated closed curves excluding such inspecting points (for example, inspecting points indicated by "0" marks) which are not intended to be inspected are unable to be designated. Therefore, lattice points which are not intended to be inspected are to be included. Accordingly, a target mark corresponding to an inspecting point which is not intended to be inspected is also automatically exhibited on the target mark exhibiting means, and thus the time required for measuring the visual field becomes unnecessarily long as a whole because target marks corresponding to inspecting points which are not intended to be inspected are automatically exhibited on the target mark exhibiting means. If it is attempted to designate the rectangular area 15 while excluding such inspecting points which are not intended to be tested, the rectangular area 15 must be designated in such a manner as to divide the rectangular area 15 into small portions. Therefore, there is such an inconvenience in that it takes much time for designating an area of inspecting points to be added or to be deleted.